Site Relevance

Relevancy - Everyone says that relevent links matter more. I've also heard that google likes clusters of pages that are "relevant".

How does google figure relevancy? For instance, I run an education site focused on Prek-8th grade. What does google consider relevant?

- Other education sites - do they distinguish between grade levels or elementary, middle, high, post secondary, graduate, or professional training?

- Are children a sector? Will chidlren's shopping sites be considered relevent?- Software. Is educational software relevent to games? Is web technology and marketing issues relevent to educational software? Would this link - www.time4Learning.com - count less because its in a technology / software / marketing paragraph than the link in the paragraph below?

- Subject matter - Time4Learning focuses on teaching kids language arts and math with social studies and science thrown in. We are a modern version of Hooked On Phonics minus the bogus claims and high price. We compete in terms of functionality with Kumon, Sylvan, Huntington, and the other educational systems but Time4Learning has the convenience of being home-based and is very low cost. www.Time4Learning.com remains a great deal but unfortunately, a best-kept secret. Other quality online learning programs such as SuccessMaker, Headsprout, CleverIsland, and (tbc?) cost alot more.